Common virus may yield new treatment for prostate cancer

01 March 2010

Researchers in Alberta have recently successfully tested a new way of treating prostate cancer in a small number of men using a harmless virus called reovirus. The cancer-fighting properties of the virus were originally discovered by Drs Patrick Lee and Peter Forsyth over 10 years ago with the help of Canadian Cancer Society funding. It’s a discovery that Dr. Lee still describes as the most exciting of his scientific career. When Drs Lee and Forsyth began their study, the researchers were hoping to answer the question: could a virus that commonly causes mild coughs and upset stomachs help people suffering from malignant brain tumours? To test their theory, the research team into malignant gliomas, the most common type of brain tumour. When this live virus was injected into experimental mice carrying human gliomas, the tumours either regressed completely or shrank significantly. The mice gained weight, seemed healthier and lived longer than similar mice treated with a dead virus. The reovirus also infected and killed all the cancer cells present in nine glioma samples that had been surgically removed from patients. The current study, led by researchers in Calgary, involved injecting the reovirus in six prostate cancer patients, as well as mice models and test tube experiments to examine how well the approach worked. The virus destroyed a number of cancer cells and sent out copies of itself to attack more cancer cells, but did not spread to normal cells. The virus is very specific in which cells they attack, targeting cancerous cells and leaving healthy cells alone.